Import set 1.0.0

- SortedSet has been removed for dependency and performance reasons.
- Set#join is added as a shorthand for `.to_a.join`.
- Set#<=> is added.

https://github.com/ruby/set/blob/v1.0.0/CHANGELOG.md

1 files changed, 8 insertions, 0 deletions

diff --git a/lib/set.rb b/lib/set.rb
index 625046d37c..2bd2a0ffa5 100644
--- a/lib/set.rb
+++ b/lib/set.rb
@@ -641,6 +641,12 @@ class Set
     end
   end
 
+  # Returns a string created by converting each element of the set to a string
+  # See also: Array#join
+  def join(separator=nil)
+    to_a.join(separator)
+  end
+
   InspectKey = :__inspect_key__         # :nodoc:
 
   # Returns a string containing a human-readable representation of the
@@ -684,3 +690,5 @@ module Enumerable
     klass.new(self, *args, &block)
   end
 end
+
+autoload :SortedSet, "#{__dir__}/set/sorted_set"